Prior art patents disclose anti-siphoning devices for preventing unauthorized removal of liquid from a storage tank. One method of preventing siphoning is to partially block access to the storage tank so that the tank can be filled but a siphoning hose may not be inserted into the tank to siphon away liquid.
A typical prior art method for blocking the tank inlet is to mount an insert near the inlet that allows a fuel dispensing device to be inserted into the inlet but prevents insertion of a siphoning hose.
Italian Pat. No. 461,298 to Stratta illustrates one such anti-siphoning device. This patent discloses a cylindrical receptacle connected to a fuel tank inlet. The receptacle bottom has small holes that allow liquid to pass to the tank, but which prevent an extraction tube from being inserted in the tank. Exensions formed in the side of the receptacle engage a flange formed in the tank inlet to prevent withdrawal of the anti-siphoning device.
The prior art anit-siphoning devices such as the apparatus disclosed in the Stratta Patent require modification of the tank inlet to accommodate the anti-siphoning devices. The Stratta tank inlet must include a flange that prevents withdrawl of the anti-siphoning device from the inlet. An additional drawback in these devices is that many can only be installed with special tools for disassembling or modifying structure on either the tank inlet or the anti-siphoning device. The Stratta Patent refers, for example, to the use of rivets or pins to hold the insert in place. Applicant is unaware of a truly easy-to-install yet effective anti-siphoning device for an existing liquid storage tank.